A couple of days ago, the Tustin Hummer page in Google maps even mentioned the addition of Mike Sabbarese to their service dept. It's not there anymore, but here's a
google cache mentioning the same. Again, no idea how Tustin service will do. But if you can get to speak & explain your problems to Mike personally, you'd have a fighting chance of finally fixing the problem, imho. Oh, and I'd keep calling rather than leaving a vm (Mike isn't that great at returning phone calls either).